Electrochemically controlled growth of Au-Pt alloy nanowires and nanodendrites.

The ability to control the morphology and phase structure of alloy nanowires is essential for the exploitation of their unique functional properties. This report describes the findings of an investigation of the growth mechanism in the electrochemically controlled growth of Au-Pt alloy nanostructures. By using a template-free alternating-current deposition method with different combinations of waveform, voltage, and frequency, controllability over the alloy morphology, composition, and phase structure has been clearly demonstrated for the growth of the nanostructures across the gap of two microelectrodes. The growth is proposed to involve an initial facet-selective nucleation-growth process followed by two competing nucleation-growth pathways that are highly tunable by the applied frequency and voltage. The findings provided new insights into the mechanism that underlies the controlled fabrication of alloy nanowires and nanodendrites with structurally tailorable functional properties.

7-Ethyl-10-hydroxycamptothecin proliposomes with a novel preparation method: optimized formulation, characterization and in-vivo evaluation.

CONTEXT: The proliposomes were used to solve the stability of the ordinary liposomes. OBJECTIVE: 7-ethyl-10-hydroxycamptothecin (SN-38) proliposomes for intravenous (i.v.) administration were prepared successfully by a new method. MATERIALS AND METHODS: SN-38 liposomes solution was reconstituting automatically from proliposomes on contact with the acetic acid buffer solution (0.2 M, pH 2.6). The formulation was optimized by the Box-Behnken design. The physicochemical characteristics of the SN-38 proliposomes were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The stability studies were also carried on. The FLU-HPLC system was served to study the concentration of SN-38 in the plasma of Sprague Dawley (SD) rats. RESULTS: The optimized formulation was SN-38: 0.03 g; Soybean phospholipid (SP): 0.6 g; dextrose: 3.00 g. The entrapment efficiency of the optimized formulation was >85% and the mean particle size was about 231 nm. The stability studies showed that SN-38 proliposomes were stable in dark at 20-25°C for 6 months at least. The pharmacokinetic parameters of i.v. administration demonstrated that the half-life of SN-38 loaded in the liposomes was prolonged in vivo. DISCUSSION AND CONCLUSION: The SN-38 proliposomes was prepared successful by the analysis of TEM, SEM, DSC and XRD, and SN-38 liposomes could be reconstituted on contact with the hydration medium. SN-38 liposomes circulated for a longer time in the blood circulating system than SN-38 solution, which contributed to maintaining the drug action.

The pharmacokinetics and metabolism study of sodium 7,4' -oxo-acetic acid daidzein in rat.

OBJECT: To Study the pharmacokinetics and metabolism of Sodium 7,4' -oxo-acetic acid daidzein in rat. METHOD: Sodium 7,4' -oxo-acetic acid daidzein was determined by reversed-phase HPLC (column: German CenturySIL BDS C18 5 µm silica, 200 mm x 4.6 mm i.d; fluid: methanol-water-85% phosphoric acid(57:43:0.05, v/v/v)), with sodium benzoic acid as an internal standard. Biological samples were extracted with acetonitrile. RESULTS: The calibration curve was linear over the range of 1.0-1000 µg/ml in rat plasma, urine and feces. The average extraction recoveries were 73.3% (plasma), 73.9% (urine) and 83.7% (feces) respectively and the intra-day and inter-day precisions were less than 8.34%. The assay was applied to the analysis of samples from a pharmacokinetic study. The absolute bioavailability of oral administration was 3.07%. DZ I original compound determined in 6h urine was 32.32%, in 24h urine was 32.71%, in 24h feces was 22.96%.